According to the 2010 Americans with Disability report from the U.S. Census Bureau, roughly 30.6 million individuals aged 15 years and older (12.6% of the U.S. population) had limitations associated with ambulatory activities of the lower body including difficulty walking. About 23.9 million people (9.9% of the U.S. population) had difficulty walking a quarter of a mile, including 13.1 million who could not perform this activity. This represents a significant healthcare, societal and economic problem as these people are at significant risk of developing co-morbidities, rapidly declining health, and face significant challenges associated with integrating into the community and re-joining the workforce. Neurological disorders such as Parkinson Disease (“PD”) and stroke are significant contributors to this large and growing segment of the population. An estimated 5 million people throughout the world have PD with about one million living in the United States and the number of individuals with PD is expected to double from 2005 to 2030. Every year, more than 795,000 people in the United States have a stroke, with approximately 87% of these strokes being ischemic (thrombotic and embolic). The 30 day mortality following an ischemic stroke is approximately 10%, meaning that the remaining 90% live with disabilities, resulting in upwards of 7 million stroke survivors living in the United States today. The costs of these two diseases to the United States are significant, with estimated annual costs of $38.6 billion for stroke and $23 billion for Parkinson Disease. Disorders, such as muscular dystrophy, polio, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), spinal cord injury, cerebral palsy, or age-related deterioration also present varied degrees of mobility impairment. Some disorders, such as ALS, present issues of progressive mobility impairment that change and worsen over time.
As to stroke patients, many patients are capable of ambulation, but struggle with slow, fatigue-inducing gait patterns resulting from weakened ankle dorsiflexion and plantar flexion, as well as reduced movement during hip flexion and extension. Persons recovering from ischemic stroke in the middle cerebral artery (MCA) often suffer from diminished lower-extremity abilities, exhibiting hemiparesis and limited endurance.
Patients who have suffered severe lower extremity trauma (including polytrauma) will often undergo major reconstructive surgery to repair damaged skeletal and soft tissue (including peripheral nerves) in an effort to enable them to ambulate independently. Other mechanisms of injury that affect patient mobility are mild TBI (loss of coordination movement), severe TBI (loss of muscle force generation capacity), stroke and other neuromuscular disorders.
A pressing need exists for effective interventions for persons with mobility impairments, including impairments resulting from, but not limited to, Parkinson's disease, stroke, muscular dystrophy, polio, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), spinal cord injury, cerebral palsy, and/or age-related deterioration. Taking impairments resulting from PD and stroke as illustrative examples, these diseases have different underlying causes and presentations, yet present similar co-morbidities and consequences on quality of life. Despite medical and surgical interventions for PD patients, they face deterioration in mobility over time resulting in a loss of independence and a decline in health related quality of life (HRQoL). Deterioration of walking is perhaps the most important single factor contributing to decline in HRQoL. In one study, a significant decrease (12%) in the number of steps (effect size=0.28) walked per day over the course of one year highlights the rapid decline in walking ability that occurs with disease progression. In stroke, an infarction in the middle cerebral artery (MCA) is the most common site of cerebral ischemic. Most persons regain some ability to ambulate following physical therapy; however, they often require rigid braces (ankle-foot orthoses) and various forms of assistive devices (i.e., walkers and canes), which limit walking efficiency. Walking is slow, labor intensive and inefficient, with most persons post-stroke ambulating slower than about 0.8 meters/second.
Such limited walking speeds after stroke can restrict individuals to the household and limit reintegration into the community. It is therefore not surprising that the restoration of walking function is the ultimate goal of rehabilitation for the majority of stroke survivors and the focus of much rehabilitation research. However, current therapies are often unable to improve subjects' community ambulation status, regardless of the mode or sophistication of the training as walking deficits persist for most patients. Community-based rehabilitation programs have been proposed to address the limitations of the clinic-based model; however, an evaluation of community-based outcomes demonstrates mixed results with subjects remaining largely sedentary. A simple explanation for this is that many of these programs rely heavily on patient education and motivational feedback (e.g. daily step counts) to improve physical activity and do not address the specific motor impairments limiting mobility. Consequently, these programs tend to neglect the real impact that an impaired motor system has on an individual's walking ability and community engagement.
Beyond slowed walking speeds, post-stroke gait can also be characterized by altered kinematics and kinetics in both magnitude (e.g., joint angle range, peak moment, peak power) and pattern (e.g., shape and direction of curves). These deficits are more marked on the paretic side; however both limbs are often impaired. There are indications that impaired improvements in gait mechanics contribute to a higher reduced energy cost of walking and improved reduced long-distance walking ability after stroke, major factors limiting determinants of community engagement. Indeed, a hallmark of post-stroke walking is the use of inefficient compensatory strategies, such as stiff-legged and circumduction gait, to advance the body through space. Because a rapid achievement of walking independence—not necessarily the reduction of impairment—is the goal of current neuro-rehabilitation practice, the prevalence of such compensatory strategies following rehabilitation is not surprising as gains in walking function are achievable via compensatory mechanisms.
Furthermore, current assistive devices such as canes and walkers, which are often provided during the early phases of stroke recovery to promote safe, independent ambulation, may also contribute to this reliance on compensation. Considering that compensatory strategies are known to increase the energy cost of walking, increase the risk of falls, reduce endurance, and reduce speed, gains in walking independence through such mechanisms may impose bounds on the degree of community reintegration possible after stroke. The impact on post-stroke physical activity of such walking deficits is evidenced in a markedly reduced total number of steps walked per day compared to even the most sedentary healthy adults. Given that reduced physical activity increases the risk of second stroke, heart disease, diabetes, hypertension and depression, and is further associated with a reduced health-related quality of life, a need exists for the development of interventions that directly modify walking ability in a manner that facilitates long term improved physical activity, ultimately building healthier lives for persons after stroke.
A chief limitation of the current rehabilitation model is that training and evaluation often occur in the confines of the clinic and are often divorced from the constraints and demands of a patient's home and daily environment. For example, recent intervention studies have demonstrated marked improvements in clinic-measured walking speed without concurrent translation of these improvements in community ambulation. Beyond poor ecological validity, current efforts are also limited by logistical and economic constraints. For example, current reimbursement models are such that after a stroke, patients only receive physical therapy in outpatient centers for 10-12 weeks, after which individuals typically do not participate in a rehabilitation program. During these 10-12 weeks, the frequency of therapy is often limited to only 3-5 sessions per week. Thus, subjects may amass between 30 to 60 total sessions during the course of their rehabilitation—with much, if not all, taking place in environmental contexts substantially different than what they encounter on a daily basis. Despite rehabilitation efforts, marked physical inactivity is emblematic of persons post-stroke and continues to worsen across the first year after occurrence. Thus, effective interventions focused on improving mobility (e.g., restoring more natural motion) for an affected patient having a gait impairment or disorder is a significant factor in reducing their disability, improving integration with the community and improving HRQoL.
Difficulty with walking is frequently followed by problems with gait-dependent activities such as housework, dressing, transferring in and out of bed. For patients with neurological disorders, limited gait velocity commonly results in walking that is predominantly restricted to the household with limited reintegration into the community.
The clinical hallmarks of Parkinson disease include resting tremor, rigidity (i.e., stiffness), bradykinesia (i.e., slowness of movement) and gait disturbance. Pathologically, PD is characterized by degeneration of dopaminergic neurons in the substantia nigra of the midbrain. As a result of this deficiency, there is a loss of the normal internal cueing mechanism resulting in lack of automaticity and synchronization of movement. This contributes to the characteristic gait of persons with PD—impaired regulation of stride length, reduced gait speed, altered cadence and stride time variability. This is in part due to a decreased rate of torque generation in the plantar flexors during terminal stance. Dopamine replacement therapy, the gold standard pharmacological treatment in PD, is ineffective in remediating step frequency and gait variability.
A stroke patient's gait is characterized by a decrease in self-selected speed and previous studies have reported altered kinematics and kinetics in both magnitude (e.g., joint angle range, peak moment, peak power) and pattern (i.e., shape and direction of curves). In addition, while there are reported reductions in both legs, there is typically a greater reduction on the paretic side. Compared to healthy adults, walking patterns post-stroke are also commonly associated with greater physiological effort during walking. One of the primary factors contributing to these abnormal walking patterns in persons post stroke in the MCA distribution is the impaired functions of the distal limb musculature (e.g., ankle joint plantarflexors or calf muscles) of the involved paretic leg.
For all these conditions, a challenge for caregivers is to restore a patient's physical function in order to minimize the delay they face for returning to normal activities while they complete a rehabilitation program, which can typically be expected to take 3-6 months. The medical consequences of restricted mobility are staggering. Complications associated with immobility affect the musculoskeletal system (e.g., atrophy, osteoporosis, etc.), respiratory system (e.g., pulmonary embolism, decreased ventilation, etc.), vasculature (e.g., deep vein thrombosis, etc.), skin (e.g., pressure sores, tissue breakdown, infection, etc.) and the patient's mental state.
Conventional wheelchairs are often employed to help individuals to move. However these offer little benefit in terms of exercise for the legs of the user. To exercise the legs, walkers are frequently used, which users are able to lean on and hold on to as they move about. Walkers such as these cause upper body strain, as the user often must lean heavily on the handles of the walker in order to reduce his or her weight enough to move without severe discomfort. Therefore, there is a need to change this paradigm such that a user need not rely heavily on leaning on a walker in order to move without discomfort. Approaches that make provision for an external source of power (i.e. motorized wheels) that would propel the patient horizontally ignore any potential rehabilitative, therapeutic effects by leaving the patient out of the propulsion process.
Indeed, mobility aids were designed as a means of assisting individuals that experienced decreased leg strength or deformities; however, during the recovery process of these individuals, durable medical equipment companies most often supplied them with either the conventional handheld walker, rolling walker, walking cane, or crutches individually, but none of those devices were capable of supplying the assistance required for the rehabilitation of weak legs when so many other areas of the body needing support was totally neglected. Originally, these devices were thought to give sufficient stability and support; however, since an adequate sense of balance, strength in the arms, legs, wrists and back areas are also required to operate these devices, the individual using these devices would soon become exhausted and limit their activities of exercise resulting in prolonged rehabilitation.
A walker, as a mobility aid has stability due to the construction of the base, but since the stability feature of that walker is limited to stabilizing the walker and not the individual user, it is not sufficiently accommodating alone to provide adequate assistance in the mobilization of an individual. The resulting effects generally produced significant postural and back problems or injury due to the lack of proper body alignment and support.
Crutches, have a definite advantage over a walker, because they provide more contact points between the device and the individual user, wherein means to relieve stress from the back areas and weight off the legs is provided. But crutches alone hinder the endurance of the weak, because most of the individuals energy is used lifting the crutches with each step taken.
Whether a mobility aid is built for walking, standing or to minimize the ambulatory efforts of the individual user, safety should always be considered a crucial factor during production and selection of a device. There are rolling platforms, canes and walkers that seek to help movement of persons having limited mobility who can remain in an upright, standing position.
U.S. Patent Application Publication No. 2013/0197,407 provides for a system for gait training, which includes a height-adjustable rolling platform for attaching to the foot with or without a shoe, on the affected side of a subject. When the subject shifts their body weight away from the affected side, the platform is capable of forward and backward movement to follow the swinging movement of the leg. When the subject shifts their body weight to the affected side, a passive braking system arrests any further movement of the affected limb.
U.S. Pat. No. 9,016,297 provides for a quad-wheeled and quad-legged cane. The cane typically includes one or more wheels, one or more rigid supporting structures, and one or more handles. The wheels of the cane are preferably retractable. The rigid support structures preferably overhang the wheels and generally provides fail-safe braking. The handles may be adjustable
U.S. Pat. No. 4,029,311 provides for an invalid walker having a lightweight, rigid frame having improved steerability derived from a combination of uniquely steerable front casters having upwardly and forwardly slanted swivel shafts together with non-swiveling rear wheels that are independently and separately controlled by separate right and left-hand brakes. Simple, effective brakes for each wheel embody a tubing section held in place solely by a return spring and the hand-operated brake cable.
U.S. Pat. No. 9,132,056 provides a crutch with wheels and a frame structure with a straight front frame part, a curved rear frame part and a strut extending between the straight front frame part and the curved rear frame part. A handle is provided in the upper part of the front frame part and a wheel is provided in the lower part of the front frame part. The upper part of the rear frame part is connected to the front frame part and a pair of wheels is provided in the lower part of the rear frame part. A tubular part is fixed to the lower part of the handle, which tubular part is detachably insertable into or over the upper end of the front frame part and in that a lower part of the tubular part is designed for connection to a ferrule when the handle is withdrawn from the front frame part.
U.S. Pat. No. 5,62,762 provides a walker with a non-rotatable glide assembly that easily slides over the ground surface when a walker is lifted and advanced forwardly. As soon as a predetermined downward force is exerted on the walker legs, the glides retract and non-slip crutch tips engage the ground surface. Moreover, an individual glide may be easily removed and substituted by a wheel that provides rolling contact with the ground surface. The remainder of the mounting structure is used so that the walker may be easily converted from a glide to wheeled arrangement.